Mosquito threat looming in Brockton area

State and regional health officials say they have no way to predict what residents can expect this year from the threat of Eastern equine encephalitis.

But one thing is certain.

“The rains that we got this spring certainly aren’t good,” said David Flaherty, health agent for Raynham.

“It looks like it’s going to be a bad year (for mosquitoes),” said Tony Texeira, superintendent of the Plymouth County Mosquito Control Project, which has already sprayed about 12,000 acres of wetland and swamp areas this spring to kill mosquito larvae. Ground spraying traditionally continues until Labor day, he said.

Health officials say they will know more about this year’s mosquito population by Monday, when they will have two weeks of data gathered.

On Friday, the state announced its first discovery of West Nile virus, found in a sample of mosquitoes taken from a pool in Whitman June 25. No mosquitoes have tested positive yet for EEE.

Last summer, state public health officials lowered the threshold from “critical” to “high” for when to aerial spray, actuated by a group of southeastern Massachusetts health agents who urged the state to take more proactive measures.

Also last summer, the state saw the disease rear its head earlier than is typical; by July 9, the virus had infected four mosquitoes, two bird-biting and two mammal-biting, found in samples collected in Easton along the Raynham and Taunton borders.

By mid-July, 21 communities throughout Southeastern Massachusetts were earmarked for aerial spraying to target the diseased-carrying mosquitoes.

High-risk towns, paralyzed by the threat of a single mosquito bite, initiated 7 p.m. curfews at the state’s urging.

And authorities were left shaking their heads as to why the pattern they had seen since 1938 (when surveillance began) no longer seemed to hold true.

“It used to be Eastern equine encephalitis would go away for several years and then come back. That was the pattern we saw since 1938,” Sam Telford III, a biologist and professor of infectious diseases at Tufts University said Friday.

State health officials, in May 2012, announced that the number of people in Massachusetts who had contracted EEE had grown in recent years, according to ongoing studies.

Data showed that historically long gaps between cases were narrowing; 5 human cases were reported in 2006, followed by two human cases in 2010 and two more in 2011.

In 2012, seven people contracted the disease, including two who died: a 63-year-old Amesbury woman and a Westborough man in his 70s. Another 33 Massachusetts residents were infected last year with West Nile virus.

Telford, of Tufts, who began a three-year research project last year to study mammal-biting mosquitoes, said he has “A hundred bucks on the table” that EEE will be found in mosquitoes again this year.

“But that doesn’t necessarily translate to risk,” said Telford.

Bird-biting mosquitoes, or C. melanura, which breed and feed within white cedar and red maple swamps, such as the Hockomock, pick up the virus from infected birds.

Humans are at risk when the disease spreads to mammal-biting mosquitoes, through a bridge mosquito known to bite both birds and mammals.

This year, the state began testing June 17, and will continue testing statewide pools five days a week until the threat is eliminated with the first frost this fall.

“High, prolonged heat is good for mosquitoes and good for the virus. If that persists, that could potentially be a problem,” said Dr. Catherine Brown, state public health veterinarian.

While no mosquitoes have tested positive for EEE so far, officials are taking precautions and urging residents to protect themselves.

In Raynham, where 80-year-old resident Martin Newfield died after contracting the disease in 2011 (the first state resident to die from EEE since 2006), authorities have already begun doling out free bug spray through the town’s Board of Health courtesy of Wal-Mart, which began donating supplies following Newfield’s death.

Dr. Les Linares, chief of infectious diseases at Good Samaritan Medical Center has already screened several people for EEE who showed symptoms.

And local mosquito projects are taking calls from residents who want their property sprayed.

“Bottom line,” said Brown, of the DPH: “We plan for the worst and hope for the best.”

Amy Carboneau may be reached at acarboneau@enterprisenews.com or follow on Twitter @Carboneau_ENT.

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